Conventional work vehicles such as wheel loader, bulldozer and hydraulic excavator include a cab (operator compartment) as an operator's room that is composed of square steel pipes or deformed steel pipes, panels and the like that are coupled to each other.
For example, Japanese Patent Laid-Open Publication No. 2002-249073 (published on Sep. 3, 2002) discloses a roof structure of a work vehicle cab that, in order to prevent that an outer roof composing a roof surface of a cab hangs down or is dented, includes a band plate of spring steel on an interior side of the outer roof.